Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit Description
The body control module (BCM) controls various accessories through the retained accessory power (RAP) relay circuit. When the ignition switch is in either the ACC or the ON position, the BCM provides battery negative voltage to the RAP relay control circuit. When the RAP relay is energized, it supplies a B+ to the accessories not controlled by a serial data power mode message.
When the ignition switch turns from ON or ACC to OFF, with all of the vehicle doors closed, the BCM keeps the relay energized for 10 minutes, or until any vehicle door opens.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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